Native Painted Turtles (cpb) 2008-2017

Statistical Analysis of a turtle population "Chysemmys picta belli" at two locations in the pacific north west surveyed between 2008 and 2017

Data cleaning and new features

data cleaning and aggregation

Species are recorded to either Cbp (native painted turtle) or Res (red eared sliders). This analysis only looks at Cbp-Native-Turtles

Gravid True female turtle carrying eggs

Sex m, f or unknown

Carapace, Plastron, Weight cleaned decimals.. only decimals >0 utilized in analysis

Weight a value > 0 means recorded survey. Value = 0 means repeat sighting and not relevant for analisis

new features

new_annuli it is very hard to count the annuli for older surveys accurately. Different surveyors might come up with different annuli values for the same turtle. Further, it becomes harder the older the turtle gets. Thus for some old turtles, it is impossible to assess the annuli. For that reason, a new feature new_annuli is created. We conservatively take the lowest ever counted annuli for an individual turtle and then increment its annuli for each sighting in the following years. Pseudo Code:

new_annuli = (year_of_sighting - year_of_very_fist_sighting) + lowest_annuli_ever_recorded

gender_plus m, f, f_gra, unknown (distinguishes non-gravid and gravid females)

gender_seasons m_fal, m_spr, f_spr, f_fala, f_gra, unknown distinguishes seasons "fall" and "spring"

EDA - Exploratory Data Analysis

basic metrics (sanity check that the data loaded correct)

Swarmplots

Swarmplots to show distribution of Carapace, Plastron and Weight by Gender

The following plot shows: the min/max size(weight) for each sex as well as how much diversity there is in weights in a given population. Most males are under 400g, females peak at 400 and 1000g.

ECDF Graph of size/weight distribution by sex

Shows the difference in size/weight distributions between sexes; males have a nice bell curve with an even growth rate throughout life; females have 2 bumps one at 400g/150mm carapace and plastron and the other at 1000g, and 200mm shell size.

Weight, Carapace and Plastron distibution by sex

Weight, carapace and plastron show the same pattern - females ultimately grow larger and heavier than males. Trapping will show a greater diversity in female sizes/weights than with males.

Outliers

Female size/weight vs age

Shows similar pattern to the ECDF graphs - females show 2 distinct "bumps" suggesting that there are two concentrations of female animals in the population.

Males size/weight vs age

Males show one concentration of animals, suggesting a "normal bell curve" distribution.

Scatterplots to show metrics per survey location + linear regression

Weight distributions across 2 separate populations

The hypothesis: same distribution in all capture locations proved true

Correlations between annuli, size and weight.

Annuli is less of a predictor of an animals size/weight, however, size and weight are strongly correlated.

Distribution of weights and sizes by sex, separating out gravid and non-gravid females

(...)

Scatterplot graph showing correlation of annuli with size/weights of animals by sex with gravid females separated out from non-gravid females.

Same as above - showing relationship between size/weight and age for gravid females, non-gravid females, males and unknowns.

Scatterplot showing distribution of sizes and weights as a function of which season the female data was collected.

Same as the two graphs above. Shows distribution of sizes and weights and separates out females in to 3 groups (non-gravid spring, gravid spring and fall measurements) as well as males and unknowns.

Comparison of size/weight distributions across seasons between Gresham and Mason Flats populations

Comparison of size/weight distributions by sex for animals caught in the spring vs fall between two populations (Gresham and Mason Flats).

Comparison of size/weight distributions across seasons between Gresham and Mason Flats populations

Same as above graphs, but with higher-order polynomial regression lines. Comparison of size/weight distributions by sex for animals caught in the spring vs fall between two populations (Gresham and Mason Flats). Males show no real difference in distribution between populations or seasons. Females have a greater diversity of sizes/weights and are heavier in fall vs spring, with gravid females being the heaviest on average.